My climate is high desert, zone 3-5 - not exactly the natural habitat of Vandas haha definitely cooler than they'd like but I do get a fair amount of sunlight.
For the winter, I've been hanging them in a south facing window where they probably get 5-6 hours of direct sunlight a day. This will be too intense come summer, but so far the leaves aren't damaged and its the most warmth I can provide for them.